The private company Mars One plans on sending four people on a one-way trip to Mars in 2025 on a $6 billion budget.

Neil deGrasse Tyson, famous astrophysicist and host of the new National Geographic show StarTalkTV, is not signing up for that trip.

Mars One made headlines in February when it announced the top 100 candidates for the trip, but its business model and timeline for the mission are overly optimistic at best.

"I try not to get in anybody's way who is dreaming big," Tyson told Business Insider. "But I'm skeptical that it can be accomplished on the timescale that they say."

Many scientists, astronauts, and other public figures are pushing for a Mars mission. Tyson had a great explanation for why we want to get there so badly, and why we're not ready yet.

"My sense is that there is an urge to create the same kind of pioneering spirit as what existed in the 17th century when the pilgrims came to Plymouth Rock," Tyson said.

The problem is that there's a huge difference between the first Europeans who traveled to America and the first humans that would travel to Mars. Even though the pilgrims knew they were also on a one-way trip, when they stepped off the boat they could still breathe the air and the trees were still made of wood so they could repair their ship, Tyson said in an interview in his office at the American Museum of Natural History.

But if you go to Mars you can't breathe the air and you can't just repair your ship — the first thing you’re gonna do is set up a hab module that resembles Earth," Tyson said. "Well then are you really on Mars? No — you’re on Earth on Mars."

For whatever reason Mars One wants to build camp on Mars, Tyson said their current business model doesn't look sustainable. Mars One is planning on paying for the mission through sponsors and a reality TV show starring the settlers, but it's having trouble getting much investment interest. So far the company has raised barely over 0.01% of it's $6 billion budget.

Tyson has a hunch for why Mars One is struggling to find investors:

"If I'm a venture capitalist, I would ask you a series of questions," Tyson said. "I would say:

Is it dangerous? Well, yes.

Will people die? Probably.

How much will it cost? I don't know, but a lot.

What's my return on investment? Nothing.

That’s a quick conversation."

So Tyson won't be signing up for the trip.

"But I'm not going to stop them," Tyson said. "Somebody's gotta go and do this first you know."